Railway-train-despatching circuit.



W. REfD.

RAILWAY TRAIN DESPATCHING CIRCUIT. APPLICATION FILED SEPT.8. 1914.

1 ,266, 1 58. Patented May 14, 1918.

I g ether through t WILLIAM REID, OF CHICAGO, ILLIN 'IS. ASSIGNOR T0 KEL COMPANY, OF CHICA O. LI INDIE A CORPORATION OF ILLINOIS.

RAILWA l:

Specification 01 Letters Patent.

W-DESPATCHING CIRCUIT.

Patented May,14, 1918.

Application filed September 8, 1914. Serial No. 860,600.

I! '0 all whom it may concern.

Be it known that I, l ImJAM REID, a citizen of the United States of America, residing at Chicago, irnthe county of Cook-and State of Illinois, have invented certain new and useful Improvements in Railway-Train- Dcspatching ircuits, of which the followin is a specification. I

lily invention relates to telephone transmission systems and more particularly to that class of transmission systems of use in connection with railway train despatching circuits. My invention is particularly designed to provide a balanced receiving circuit so that a standard type of telephone receiver may he employed.

My invention also contemplates provid ing as much impedance as possible for the receiver circuit so that the operator when listening may readily break in for outgoing transmission should he so desire.

The circuit is also so arranged that the receiver circuit bridge is never interrupted even when changing the circuit from incoming to outgoing. I further arrange the sec' ondary of the induction coil in a separate and independent brid e.

I will explain one Ollll which my invention may take more in detail by referrin to the accompanying drawing illustrating ciagrammatically a line circuit with two substation circuits in place.

In the drawing I show two line conductors 1 and 2 which are adapted to extend along the railroad ri we. in casethe circuit is used for tram despatc i There are of course as many substation circuits as needed only two bei here set out as be' suflicient for illustrativipurposesi The substation talkingsets are esirably Ill identical. have as stated shown two substations A and B, each provided with a transmitter 3 arranged in a local circuit includ' the primary windi g 4 of the induction col the attery 5, and the contact springs 6 and 7 adapted to be efiodically connected toe agency of the button 8.

he button 8 also actuates anldclitionel contact spring!) associated respectively with contact s rings 10' and 11 for purposes which :ril prescntlv appear. The secondary winding 12 of the induction coil is a aptcd for connection in In ind 1 wt bridge across the line eonfl ptmc and 2 S1011 whenever the c ange the springs respectively with adjustable cores 18 and 19 hcl in position by the set screws 20.

The impedance of the circuit can thus be arranged in such a way :1 to accommodate for the conditions existing at that partic ular station and the receiver circuit can thus be well balanced. A conductor 21 extends from a connection preferably centrally between the windings 15 and 16 to the contact spring 10. For incoming voice current: therefore, or incoming transmission, the receiver 13 is in series only with the condenser 14 and the coil 15 these three serially included devices being in an independent bridge across the line conductors l and 2.

Now when the operator at the station A for instance wishes to break in, meaning thereby to arrange this circuit for outgoing transmission. he :u-tnatcs th button 8 to more the springs and 9 to their alternative position. whc upon iinadditional i|n-- parlance winding i is rmh included in the receiver bridge between the conductors l and 2 and the local transmitter circuit is closed. For outgoing transmission therefore the local receiver circuit has its impedance increased without having,' this receiver circuit intcrr'uptcd. To return to the incoming transmi sion arrangement the button 8 is returnc l to thc po ition shown, whereupon the llcal 1ransmi1tcr circuit is opened the circuit of tin,- secondary winding 12 is opened. and the receiver circuit has its impedance rh- Fcascd.

From what has been rhfit'rihcd the nature of my invention will he rcadily apparent to those skilled in the art. and having thus lcscribed one form which my invention may take what I claim as new and desire to secure by Lctters Patient is:

I. A telephone transmisdo'n System comprising a plurality of stations united bya LOGG SWITCHBOABD 8c SUPPLY LOO 80 also included in an shunt circuit thereby increasing common line circuit, each station having a local transmitter circuit including a battery and a primary winding of an induction coil, a secondary winding for said coil included in a normally open bridge across said line circuit, an independent permanent bridge across said line circuit normally including a receiver and an adjustable impedance coil, and a second impedance coil, a shunt about saidsecond in'ipcdance coil, a movable contact for increasing the impedance of the receiver brid e by remorin said shunt from around sai second impedance coil and for closin said normally open bridge across said line circuit.

2. A telephone transmission system comprising a plurality of stations united by a common line circuit. each station baring it local transmittin circuit including the pri-' mary winding 0 an induction coil, a secondary Winding for said coil included in an open ridge across said linc circuit, an in dependent bridge across said line circuit including a pair of impedance coils and a receiver, a normally closed shunt circuit around one of said impedance coils, and a movable switch contact for opening said the impedclosin oi, sai

once of the receiver bridge and for said normally open bridge in shunt receiver bridpe.

25. A telcpione system phone line, a substation connector including a tcle said inc a secondary winding included in :1 nor:

mal y open bridge across said line circuit, a receiver included in an independent normally closed bridge across said line circuit. a pair of adjustable inipedance coils in suit last bridge, a movable switch contact included in a normally closed circuit about one of said impedance coils and adapted to be included in the circuit of said secondary coil, and means for operating said switch contact to increase the impedance of the rc-- ceiver bridge by placin said impedance coils in series, said spitci contact. also operable to close said normally open circuit. including the secondary coil.

Signed by me at (thicag o. county oi (Tool; and State of l-llinoie, in the presen e oi inn WliltG?.-

VVlLLl A M RE i T).

Witnesses GEORGE E. Uranium, B. OBnmn. 

